Radio frequency identification (RFID) technology has been widely used in industrial automation, commercial automation, transportation and control management, and many other fields. More and more researches study UHF RFID systems to achieve long-distance, high efficiency, low cost and other characteristics. Because RFID has the advantages of non-contact, low cost, high security and mass production, traditional two-dimensional bar codes are gradually replaced by RFID. These days, radio frequency identification (RFID) is also widely used in identity identification, access control, vehicle management, warehousing logistics, retail, security management, forest management, and many other fields. A common microstrip antenna itself has the shortcomings of narrow frequency, resulting in many restrictions on the antenna design. Most are designed for a single frequency and a narrow frequency response. UHF electronic tags often use printed antennas. The majority are microstrip antennas and printing strip dipoles. This structure is mainly applied to the surfaces of goods, commodities, books and other non-metal objects. If it is applied to metal surfaces, such as metal labels, cars (motorcycle) license plates, power facilities and other fields, the signal is easily reflected to result in abnormal reception. Sometimes, the electronic tag cannot be operated and read. At present, some advanced countries, metal surface electronic tag technology has been developed maturely and has been widely used in various fields of logistics. In other countries, UHF electronic tags are already very popular, but few of the electronic tags are really used for metal surfaces. Taiwan Patent No. I479735 discloses a “long-distance radio frequency identification metal product manufacturing method and structure thereof”. Through a metal sheet of the metal product serves as a metal antenna body. The metal antenna body is provided with a resonant cavity to form a metal first antenna. A microstrip loop serves as a metal second antenna. After the preparation of the electronic tag module, the metal second antenna is attached to the metal first antenna and resonates with the resonant cavity. Finally, through the surface of the metal first antenna is processed with anti-interference, so that the internal electronic tag (UHF RFID TAG) of the metal radio frequency identification product can be activated without metal interferences to generate a better field pattern. The effective read distance is up to 10 meters. Although the above-mentioned patent can solve the problem that electronic tags are susceptible to metal interferences and have the effect of long-distance reading and sending signals, however, the preparation of the metal first antenna and the attachment and sealing process of the electronic tag are very complex, and the manufacturing cost is high to affect the population of the products. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.